1. Field of the Invention
The present invention relates to a servo control method for a video signal recorder/reproducer and an apparatus therefor. More particularly, the present invention relates to a reproduction control method in a video cassette recorder (VCR) which reduces noise generated during a high-speed search of a picture in the VCR, and an apparatus therefor. Additionally, the present invention relates to an apparatus and a method for removing a noise bar adopting the tape reproduction control apparatus.
2. Description of the Related Arts
Generally, a head gap of a video cassette recorder (VCR) is arranged on a drum such that the recorded pattern made by a head is not perpendicular to the video track of a tape, but rather forms an angle with the direction across the video track of a tape, which is called an azimuth angle. In a VHS system, the azimuth angle is 60 .degree. . Furthermore, two video heads mounted on opposite sidse of the drum result in azimuth angles having the same magnitude but opposite directions. When playing back the video tape, the azimuth angles cause the signal read out from adjacent tracks to be zero due to a misalignment loss.
In a normal playback mode, each of the two video heads reads a magnetic pattern of one field recorded on each track reads a magnetic pattern of one field recorded on each track of the video tape exactly, since the reproducing head is parallel to the recorded pattern during the playback while traveling the video track of the tape with a traveling angle determined by the rotating speed of the drum assembly and the traveling speed of the tape under the control of a drum motor and a capstan motor. That is, each video head traces the corresponding track exactly according to the standard traveling angle, so that there is no generation of a noise bar on a screen.
However, during a high-speed search of a signal recorded on the tape, the traveling speed of the tape is greatly changed while the rotation speed of the drum is not changed. Accordingly, the traveling angle is changed from that of the normal playback mode, so that the video head does not travel along just a single track. As a result, a noise bar is displayed on the screen, since adjacent tracks have azimuth angles of opposite direction.
The reason for the generation of the noise bar during the high-speed search mode will be described with reference to FIGS. 4 and 7.
First, during a forward high-speed search mode, the traveling angle is decreased to a value which is smaller than that during the normal playback mode, since the traveling speed of the tape is increased while the rotation speed of the drum on which video heads are mounted does not change. Thus, the video head travels over a plurality of tracks. For example, when a video head of channel 2 reproduces a signal from a video track of channel 1 which is the hatched portion in FIG. 4, the reproduced signal results in a noise component due to the difference in the azimuth angles.
Also, during a reverse search mode, the traveling angle is changed from that during the normal playback mode, since the traveling direction of the tape is changed by 180.degree. and the traveling speed thereof is changed without a change in the rotation speed of the drum. Thus, when the video head of channel 1 reproduces a signal from the video track of channel 2, which is the hatched portion of FIG. 7, the reproduced signal results in a noise component due to the difference in the azimuth angle.
As described above, in the conventional VCR, the change of the traveling angle according to the change in the relative speed between the rotation speed of the drum and the traveling speed of the tape during the high-speed search mode is not compensated, which results in a noise bar on the screen.